> -----Original Message----- > From: Gerd Hoffmann [mailto:kra...@redhat.com] > Sent: Wednesday, March 26, 2014 3:59 PM > To: Gonglei (Arei) > Cc: qemu-devel@nongnu.org; Huangweidong (C) > Subject: Re: [PATCH] uhci: Lower uhci timer freq when guest is idle > > On Mi, 2014-03-26 at 11:57 +0800, arei.gong...@huawei.com wrote: > > From: Gonglei <arei.gong...@huawei.com> > > > > UHCI emulation polls the device at a freq of 1000HZ, which consumes > > 12~13% CPU even though a Windows guest is completely idle when the guest > > was configed usb1.1 tablet devcie. This solution counts accumulated NAK > > packets. when it reaches to 64, then the guest is supposed to be idle > > and the freq is lowered to 10HZ. > > > > This patch has been tested on Win7/WinXP/Win2008 guests, that reduces > > the CPU consume from 12~13% to 6~7%. > > Which qemu version did you test with? I tested it with the latest qemu upstream mainline.
BTW, I encountered the windows guest boot up failed problem which I have reported. >With any 2.0 release candidate > windows guests should suspend the usb-tablet. And possibly stop all usb > polling done by the uhci controller in case the tables is the only > device connected. Yeah, if there is no device attached uhci controller, I think we can reduce the freq, otherwise the CPU consume is waste. Best regards, -Gonglei
